May 12, 2009 Włodek Guryn 1

Physic Program with Tagged Forward Protons at STAR

Single Diffraction Dissociation (inclusive SDD cross section, leading 0 using FMS, for example)

Elastic Scattering - Roman Pots only, 10 hrs data to tape 25·106 events

• spin dependence in elastic scattering AN,, ANN;• elastic scattering (b=0.31 (GeV/c)-2, =0.01,

tot = 2-3 mb);

Central Production ((Discovery physics) -- Roman Pots + TPC, ToF, 40 hrs data to tape 1.5·105 events within acceptanceparticle production in center rapidity using tagged forward protons, -, K+K-, glueballs

May 12, 2009 Włodek Guryn 2

Implementation at RHIC

Need to reach small t and values to measure small masses of interest large *=20m, special optics and beam scraping are needed.

C-AD setup 2 days (includes contingency) Data to tape 2-3 days (includes 25% efficiency of data to tape). Hence a dedicated ~ 4-5 day run is needed (20-30 hrs data to tape)

Luminosity: at STAR 3.5·1029cm-2sec-1, at PHENIX ,*=0.7m, 1.1·1031cm-2sec-1

Polarization 60-70% because of low injection intensity 0.45·1011/bunchAlso low emittence <15·10-6m

These are ideal conditions to take high performance min bias data set for both PHENIX and STAR

May 12, 2009 Włodek Guryn 3

Status: Roman Pots Being Commissioned at STAR

Vertical Roman Pots1. The pp2pp setup has been moved to STAR and has

been integrated during Run 8 and 9.

2. We are able to take data stand alone using pp2pp triggers.

3. The pp2pp trigger is being re-commissioned because of new front end at STAR (new QT boards)

4. Si detector readout commissioning and integration is underway, fine tuning is taking place.

5. RPs were operated successfully this morning without interruption to the rest of the program.

Kin Yip

May 12, 2009 Włodek Guryn 4

Commissioning pp2pp at STAR

We are trying to do as much as possible without moving the RPs but some of the steps require that we operate with the RPs moved into the beam pipe.

1. Commissioning with the beam and RPs close to the safe high intensity limit: Few one hour runs to time Si pipe line and test zero suppression (dedicated time at STAR)

2. Run with RPs in and STAR production run to time pp2pp trigger and STAR trigger (no dedicated time needed)

3. Once trigger timed in and pp2pp production setup OK run with RPs in and a dedicated time at STAR, few 1 hr runs fro debugging and one longer run as test.

4. Very important C-AD prerequisites (#1 and #2 already discussed with Todd): • Develop a scheme to measure pp2pp optics ~1-2% level• Develop a scheme to measure luminosity ~1-2% level• An APEX experiment would be very helpful to develop pp2pp optics speeding the

setup during our dedicated time

5. If the studies with the beam halo prove sufficient we will not need special time to see real elastic collisions. So we are not requesting at this time any other dedicated time, except what we mentioned above